Re: lua crashing on unrecognized strings

[Roberto Ierusalimschy <roberto@...>]

> On Tue, Aug 25, 2009 at 4:50 PM, David Manura<dm.lua@math2.org> wrote:
> > On Mon, Aug 24, 2009 at 9:03 AM, Peter Cawley wrote:
> >> Likewise, io.open wraps fopen, and if the
> >> underlying C runtime explodes on invalid input, then so will Lua.
> >
> > I came across that a few weeks ago actually.  io.open(name, 'wa') crashed  [1].
> >
> > [1] http://luadist.svn.sourceforge.net/viewvc/luadist/trunk/dists/luadist-1.0.0/lmod/dist/log.lua?view=patch&r1=304&r2=303&pathrev=304
> >
> 
> Is that legal?
> 
> I would assumed the documented behaviour on Linux
> 
> ERRORS
>        EINVAL The mode provided to fopen(), fdopen(), or freopen() was invalid.
> 
> Would be the ANSI defined behaviour.


ISO/IEC 9899:1999 (E) says this (Section 7.19.5.3):

  The argument 'mode' points to a string. If the string is one of the
  following, the file is open in the indicated mode. Otherwise, the
  behavior is undefined.

  r   open text file for reading
  ...


This is very sad, but "the behavior is undefined" actually means that.
(Even crashing is acceptable.)

-- Roberto